Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective September 2012, the GHCN-M version 3.2.0 dataset of monthly mean temperature replaced the GHCN-M version 3.1.0 monthly mean temperature dataset. Beginning with the August 2012 Global monthly State of the Climate Report, released on September 17, 2012, GHCN-M version 3.2.0 is used for NCDC climate monitoring activities, including calculation of global land surface temperature anomalies and trends. For more information about this newest version, please see the GHCN-M version 3.2.0 Technical Report.
*The GHCN-M version 3.1.0 Technical Report was revised on September 5, 2012 to accurately reflect the changes incorporated in that version. Previously that report incorrectly included discussion of changes to the Pairwise Homogeneity Algorithm (PHA). Changes to the PHA are included in version 3.2.0 and described in the version 3.2.0 Technical Report. Please see the Frequently Asked Questions to learn more about this update.
PLEASE NOTE: The ranks and temperature anomalies in this report represent the values known at the time the report was issued. The actual ranks will change as subsequent years are added to the dataset. The anomalies themselves may change slightly as missing or erroneous data is resolved. Also, in 2009, NCDC switched to ERSST version 3b (from version 2) as a component of its global surface temperature dataset. Because the versions have slightly different methodologies, the calculated temperature anomalies will differ slightly. For more information about this switch please see the Global Surface Temperature Anomalies FAQ .
temperatures in 2004 were 0.54°C (0.97°F) above the
long-term (1880-2003) average**, ranking 2004 the fourth warmest
year on record. The warmest year on record is 1998, having an
anomaly of 0.63°C (1.13°F), followed by 2002 and 2003 both
having an anomaly of 0.56°C (1.01°F). Land temperatures in
2004 were 0.83°C (1.50°F) above average, ranking fourth in
the period of record while ocean temperatures were third warmest
with 0.42°C (0.76°F) above the 1880-2003 mean.
The map of temperature anomalies (above right) contains data
from an in-situ
and satellite blended data set of land and ocean temperatures.
The period of record for this data set is 1988-2004, a relatively
warm period compared to the base period used in the creation of the
map of temperature anomalies. Some minor differences in the
land surface anomalies between these two maps result from the
differences in base periods and data that are used to construct the
The mean Northern
Hemisphere temperature was near record levels in 2004 at
0.66°C (1.19°F), above the long-term average, 2nd warmest.
Hemisphere temperature also reflected the globally warmer
conditions, with a positive anomaly of 0.40°C (0.72°F)
above the long-term average, 6th warmest .
**The 1880-2003 average combined land and ocean annual
temperature is 13.9°C (56.9°F), the annually averaged land
temperature for the same period is 8.6°C (47.4°F), and the
long-term annually averaged sea surface temperature is 16.1°C
were above average across most land areas. The adjacent figure
depicts warmer than average temperatures (for a 1961-1990 base
period) that were widespread across much of the contiguous United
States and Alaska, as well as most of Europe and Asia. Temperatures
in these regions were 2-4°C (3.6-7.2°F) above the 1961-1990
average. This map was created using data from the Global
Historical Climatology Network, a network of more than 7,000
land surface observing stations. The only widespread areas of
negative anomalies were across western coastal areas of Australia,
central Canada and north-central Siberia where temperatures were
between 1 and 2°C (1.8-3.6°F) cooler than average.
|Notable temperature extremes in 2004 included a severe heat
wave that affected much of eastern Australia from February until
the end of March. Many city and state temperature records were set
as maximum temperatures reached 45°C (113°F). According to
the Australian Bureau of Meteorology, the spatial and temporal
extent of the heat wave was greater than that of any other February
heat wave in the Australian meteorological record, and ranked
amongst the top five Australian heat waves in any month, just short
of the January 1939 event but comparable with those of January
2001, January 1982 and December 1972/January 1973. In Spain, during
June and July, 73-year records were broken when maximum
temperatures reached between 39-42°C (104-108°F). In Japan,
a heat wave during mid-July produced a record temperature of
39°C (103°F) in Tokyo's financial district, the hottest
temperature recorded since records began in 1923.
Early in the year, extreme cold temperatures as low as 0-5°C
(32-41°F) in South Asia contributed to as many as 600 deaths
from late December 2003 into January 2004. In July, cold
temperatures were responsible for deaths of forty six children in
Peru, along with more than 100,000 farm animals and 300,000
hectares (741,000 acres) of cropland destroyed. For more
information on temperature extremes during 2004 see the annual
report of Significant
was above the 1961-1990 average in 2004, the first time in 4 years.
drier than average conditions were widespread across the
western U.S. where the multi-year drought continued to ravage the
region. India monsoon rainfall was 87 percent of normal, with the
worst regional deficit being in northwest India with 22 percent
less than average precipitation. The March-May rainy season was
shorter and drier than normal across parts of the Greater Horn of
Africa, resulting in a continuation of multi-season drought in this
region. In Kenya only 50 percent of normal rainfall has fallen in
the past two years. In Somalia, more than 600,000 people were
directly affected by the current drought and in need of food
|There were also areas of above average
precipitation in 2004. A winter storm brought heavy snowfall to
much of the Mediterranean and Middle East regions in January. The
storm blanketed areas with more than 61cm (2 feet) of snow causing
the closing of local airports, an avalanche and three deaths. In
Brazil, heavy rains that began in December and continued into
February caused floods and mudslides, leaving tens of thousands of
people homeless and killing at least 56 people. In April, a strong
storm system brought 127-178mm (5-7 inches) of rain to the
southwestern U.S. and adjacent areas in Mexico. Flash flooding of
the Escondido River in Piedras Negras caused 36 deaths and damaged
hundreds of homes. This event was characterized as some of the
worst flooding on record along the U.S.-Mexico border. For more
information about precipitation extremes during 2004, see the
annual report of Significant Events.
Additional information on other notable weather events can be
found in the Significant Events
section of this report.
Climatic Data Center is the world's largest active archive of
weather data. The preliminary temperature and precipitation
rankings are available from the center by calling: 828-271-4800.
NOAA works closely with the academic and science communities on
climate-related research projects to increase the understanding of
El Niño and improve forecasting techniques. NOAA's Climate
Prediction Center monitors, analyzes and predicts
climate events ranging from weeks to seasons for the nation.
NOAA also operates the network of data buoys and satellites that
provide vital information about the ocean waters, and initiates
research projects to improve future climate forecasts.